What will Florida nuclear power plants learn from Japan?

As federal regulators continue to look for lessons from Japan's nuclear disaster, critics are pleading for changes in three key nuclear emergency areas.

It matters to Floridians because the state has five reactors, four of which are slated to expand, with plans to build four new ones.

Evacuations: The U.S. government urged Americans within 50 miles of the Tokyo Electric Power Co.'s Fukushima Daiichi plant to evacuate, but the government only plans for 10-mile evacuation zones for U.S. nuclear sites. More than 610,000 Floridians live within 10 miles of an existing or proposed nuclear power plant. Twelve times as many — nearly 7.4 million people — live within 50 miles, according to a Sun Sentinel analysis of 2010 census data.

Outages: The top federal regulator on nuclear issues, Nuclear Regulatory Chairman Gregory Jaczko, said recently he's "not convinced" U.S. reactors could deal with power outages that last days, a condition that worsened the situation in Japan, and could lead to radiation leaks.

Nuclear waste: Some lawmakers have renewed calls for the federal government to create a national nuclear waste storage plan, after spent fuel at Fukushima overheated.

Those issues and others will be part of a review by the federal oversight agency, the Nuclear Regulatory Commission, of 104 U.S. reactors in light of the Japan disaster.

NRC officials said earlier this month after an initial review that current disaster plans don't cover combinations of emergencies, such as crises at more than one reactor at a single plant or a natural disaster that affects plants and surrounding roads or utilities. Less than a third of the country's reactors have problems with disaster plans, recent inspections found. None were significant safety risks and all have been corrected, the NRC reported.

At Florida plants, problems were found in equipment to protect plants during major floods and in procedures that would be used during blackouts.

The agency is expected to issue more findings in July and complete a deeper review in January.

Here's a look at what happened at the Fukushima plant after the March 11 tsunami and how Florida's five reactors stack up.

Emergency evacuations

Initially, Japan government officials evacuated residents within two miles of the Fukushima plant. Then they expanded the evacuation zone to 12 miles and, more recently, 19 miles.

In the event of a problem at a U.S nuclear power plant, the NRC requires state and local officials to plan for evacuations only within a 10-mile radius. But the zone could be expanded.

The NRC's order for Americans in Japan to evacuate 50 miles was based on quick calculations and "some really gross assumptions" about worst-case radiation levels, said Steve Kraft, a senior director of the Nuclear Energy Institute, which represents the nuclear power industry. The estimates were made because regulators didn't have access to detailed information, he said.

Still, there's no stopping Floridians who live outside an official evacuation zone from fleeing. That could clog roadways and prevent people closest to plants from leaving. Should the government prepare for broader evacuations just in case?

Yes, said environmental activists and others during a protest in Homestead last month opposing proposed expansions of Florida's nuclear plants.

"Nobody has planned for us to leave. Nobody outside the 10-miles circle is accounted for," said Philip Stoddard, mayor of South Miami, which is less than 20 miles away from Florida Power & Light's Turkey Point nuclear plant.

Backup power sources

A big danger with nuclear plants during disasters is the risk that they would not be able to cool the reactor core. When systems operate normally, that's done with electrical power generated by the plant. When the plant is shut down, backup generators kick in. If the backup generators are down or damaged, as some were in Japan, the cooling systems still need to run until power is restored.

NRC requires the cooling systems to operate four to eight hours. FPL and Progress' three nuclear plants are among the 44 nationwide that have battery power for four hours. FPL spokesman Michael Waldron said that's a conservative estimate because the utility could turn "shut down some nonessential equipment."

It took 12 days to restore power to all of the Fukushima plant's reactors.

Last week, Tokyo Electric Power Co., which owns the plant, also blamed the power outage for hydrogen explosions at some of the reactors: Venting systems designed to help prevent such explosions failed because they run on electricity – similar to venting systems at Florida's plants. A key difference: the buildings that house Florida's reactors are much larger than those at the Fukushima plant, so explosions are less likely.

FPL and Progress Energy have enough backup power to keep their cooling systems running for seven days. They have two backup diesel generators for each reactor, and supplies of diesel fuel to run them in concrete, steel-reinforced buildings stored high above sea level. Each of FPL's reactors has an additional cooling system powered by steam produced by the plant.

The utilities could bring in more diesel fuel to keep the generators operating and, if the generators stopped working, they could spray water on them to cool the core, as the operator of Fukushima did.

Japan's backup generators failed because of a tsunami. "Those don't happen here in Florida," said Waldron.

But some experts say one lesson from Japan is that the government and nuclear operators need to prepare for the unexpected.

"They were not expecting a five-story-high wall of water," said Charles Forsberg, executive director of the Massachusetts Institute of Technology's Nuclear Fuel Cycle Study. David Warburton, an associate professor of geology at Florida Atlantic University, said the state can't rule them out completely. There's a volcano in the Canary Islands that, in a highly unlikely scenario, could trigger a landslide in the Atlantic and generate a tsunami.

Nuclear waste storage pools

At Fukushima, the pools where spent nuclear fuel was stored began to overheat when the cooling systems stopped working. The overheating pools were blamed for fires and hydrogen explosions initially, although new information indicates that may not be the case, Forsberg said.

Florida could have a bigger problem because its spent-fuel pools are fuller than those at Fukushima, which had 1,940 tons of waste produced from six reactors as of last year, according to TEPCO.

Pools for Florida's five reactors are near capacity, with 3,199 tons of waste. Of that, FPL has moved 197 tons at the St. Lucie plant to dry casks and plans to move more this summer. These sealed steel canisters enclosed in concrete are considered less hazardous. Progress plans to move some of its spent fuel into dry casks in 2013.

Experts say more of the waste should be stored in dry casks or processed into fuel, as France does, and lawmakers should explore creating a quasi-government agency to help deal with nuclear waste storage.

Nuclear operators blame the federal government for the lack of off-site storage for nuclear waste.

Waldron said FPL agrees, but the amount of waste should be put into context: The amount generated over more than 35 years by Turkey Point would fit in a 16-by-16-foot room. Unlike the Fukushima reactors, FPL and Progress' spent fuel is not stored in the reactor building, but in a separate concrete, steel-reinforced building built to withstand hurricanes.